The present invention relates to the art of earth boring, and more particularly to a torque transmitting well tool with means for externally adjusting the spring means. The present invention is adapted for use in the drilling of oil wells, gas wells including mining and all drilling operations and the like and particularly to telescoping tools used in connection therewith. Such tools generally include an elongated outer member having a longitudinal bore therethrough and an elongated inner member telescopically mounted in this bore. The outermost end of each member is provided with conventional connecting means so that the tool can be disposed in a string or drill rod or pipe with one member connected to the upper portion of the string above the tool and the other member connected to the lower porton of the string beneath the tool. Limiting means are provided to limit the axial movement of one member with respect to the other in either direction; the distance it is permitted to move is known as the "stroke" of the tool. The tool transmits torque and the two members are splined so that relative axial movement between them is permitted while relative rotation is prevented.
One such type of telescoping tool is commonly referred to as a "bumper sub" or "impact tool" because the limiting means is comprised of two sets of opposed shoulders one of which becomes engaged or "bumps" when the moving member reaches either end of tis stroke. Bumper subs are often used to provide an upward and/or downward hammering action of relatively small magnitude or to allow a drill string to accommodate the rise and fall of a ship in offshore drilling.
Still another type of telescoping tool, often referred to as a shock or percussion tool is provided with resilient means which resist relative axial movement of the two members and provide a cushioning effect against shock. During the drilling of an oil well by the rotary method, it has become common practice to provide a section of drill collars above the drill bit. The section of drill collars provides the desired weight on the bit during drilling. The drill pipe above the section of the drill collars is generally in tension. This allows a relatively constant weight to be applied to the bit during drilling. When the hole is being started from the surface, the section of drill collars cannot be used because the length of the drill string is insufficient. A much smaller weight is therefore applied to the bit during drilling near the surface.
The action of the bit during drilling transmits shock forces to the drill string. The shock forces can be quite damaging to elements of the drill string and to drilling equipment at the surface. Drill string shock absorbers are commonly placed in the drill string to absorb the shock forces. A drill string shock absorber generally includes telescopically related parts that are separated by a spring means. The prior art shock absorbers have worked effectively with the full drilling weight on the bit. However, the prior art shock absorbers have not been effective during drilling near the surface because the weight on the bit is only a fraction of the weight on the bit at deeper depths. The spring means in the prior art shock absorbers has been too heavy to be effective during drilling near the surface.
There are other types of telescoping tools, e.g. some which combine some of the features of the tools discussed above. The previous methods of adjusting the spring settings, i.e. preload for shock absorbers and hammer-anvil gap settings for impact tools, involved tool disassembly and spring adjustment by the use of various width spacers.